French Onion Soup

Based on Julia Child’s famous recipe, this classic French Onion Soup recipe is loaded with buttery caramelized onions in a rich and savory beef broth with hints of red wine and Cognac! It’s then topped with delicious toasted cheesy bread and served right away to enjoy!

Best French Onion Soup Recipe

It’s not shocking to learn, but did you know that onion soups have actually been around since Roman times!?! Then more modern versions originated in Paris in the 18th Century, which is why this recipe is called French onion soup. Yet, it didn’t become really popular in the United States until the 1960s when there was a lot of interest in French cuisine, probably because of Julia Child. 

But what is French onion soup? In a nutshell, it’s a simple soup composed of caramelized onions and a savory beef broth that is then served with some sort of crusty bread with melted cheese floating on top. That’s it! But it’s a wonderfully rich and flavorful soup. I like to add a bit of red wine and Cognac to deepen the flavor of the broth even more with a touch of refinement. And please do use plenty of cheese! The combination of the beef broth, onions, melted cheese, and bread is like heaven!

However, this soup is really all about the caramelized onions. If you cook the onions properly the soup is amazing! If you don’t then you won’t truly produce a French onion soup. Because properly caramelizing onions is a slow process that just can’t be rushed.  However, don’t let that intimidate you. This recipe is really easy. You just need a wee bit of patience and the soup will turn out perfectly! 

• Olive Oil – I like to use olive oil, but any type of vegetable oil will work. 
• Butter – Always use unsalted butter in cooking. Yet, if you don’t have any unsalted butter on hand, just use salted butter and omit the added salt when you caramelize the onions. 
• Onion – Yellow onions, also called brown onions, are what you want to use for the most classic tasting soup. And your onions must be thinly sliced.
• Sugar – A pinch of sugar helps to speed up the caramelization process of the onions. 
• Salt – A touch of salt is needed to develop the flavors and season the soup.
• Flour – All-purpose flour is needed to make a roux, which thickens the broth. However, if you are gluten-free you could make a slurry with a few teaspoons of cornstarch and then whisk it in at the very end before adding the cheese.
• Beef Broth – To control the amount of added salt I always use low-sodium or no-sodium beef stock.
• Red Wine – Adds even more depth of flavor. I like to use a dry red wine like Cabernet Sauvignon, Merlot, or Malbec. Dry sherry is another option if you don’t have any red wine.
• Bay Leaves – An aromatic herb commonly used in soup. 
• Thyme – Use fresh sprigs of thyme for the most classic flavor. Dried thyme will work in a pinch, but it’s just not as good.
• Cognac – It’s a fancy type of brandy that adds rich flavor. But you can just use brandy or omit it altogether if you don’t have any on hand or want to splurge on this ingredient. 
• French Bread – Typically French baguette slices are always used. But any type of crusty bread cut into slices will do the trick. 
• Gruyere Cheese – This is the most commonly used cheese. Other options include Swiss cheese, provolone cheese, fontina cheese, and mozzarella cheese.
• Parmesan Cheese – Adds one final layer of indulgent cheesiness.

Making this classic soup does take a little patience to properly caramelize the onions, but it’s so worth the wait and ridiculously easy to make! Like my Beef Bourguignon, it’s the kind of recipe that is perfect for a lazy Sunday afternoon. 

You’ll need a sharp chef’s knife, a cutting board, and the onions you plan to use for your soup. First, cut off the stem and root ends of the onions. Then, remove the papery outer skin. Cut the onions in half lengthwise, from the stem end to the root end. This will help you achieve thin, even slices. Place one onion half flat side down on the cutting board. Hold the onion with your non-dominant hand, curling your fingers to form a claw-like shape to protect them while you slice. With your dominant hand, hold the knife and start slicing the onion thinly, cutting parallel to the lines of the onion. Aim for slices about ¹⁄₈-inch (3 mm) thick or thinner, depending on your preference.

The most important step of any French onion soup recipe is to caramelize the onions. So grab a large heavy pot or Dutch oven and then heat the olive oil and 2 tablespoons of butter over medium heat just until the butter is melted. Then add the sliced onions and stir them together with the butter mixture until they are fully coated.

Now, cover the pot with a lid and let the onions cook for 20 minutes over medium heat removing the lid every few minutes to stir.

Then once the onions are transparent, remove the lid and stir in the sugar and salt. Now, cook the onions with the lid off while stirring occasionally for another 40 minutes or until they are a deep golden color and sweet in taste.

Once the onions are caramelized, add the flour to the pot along with the remaining butter and stir. Now, cook everything together with the flour for about 2 to 3 minutes to remove the raw flour taste. You need to stir the mixture as it cooks.

Next, pour in 1 cup of the beef broth and then use a wooden spoon to scrape the bottom of the pot as you stir. The broth will evaporate very quickly. The idea is to loosen all the brown bits. Then add the rest of the broth along with the red wine, bay leaves, and fresh thyme sprigs. Now, bring the soup to a boil over medium-high heat, then turn the heat down, and let it simmer uncovered for 30 minutes. Then taste the soup and add more salt and black pepper if desired. Finally, stir in the Cognac.

This step is optional, but I find that it only adds to the deliciousness of the soup. First, brush the slices of bread with some olive oil and then place them on a baking sheet. Now, put the bread under the broiler to toast for about 30 seconds to a minute on each side. 

To complete the soup, you need to preheat your oven to 350°F (177°C). Then top the soup with 1 cup of the Gruyere cheese. Next, place the slices of bread over the cheese and then cover the bread with the remaining gruyere and parmesan cheese. Now, put the soup into the oven and bake it for about 20 to 25 minutes or until the cheese has melted and is starting to brown. Then ladle the French onion soup into bowls and serve it immediately.

How To Properly Caramelize Onions

Caramelizing onions for French onion soup is all about patience and love for the process. Start by choosing yellow or white onions, as they have the perfect balance of sweetness and flavor. Slice them thinly, and then it’s time to get cooking. Melt some butter or a mix of butter and olive oil in a large, heavy-bottomed pan or skillet over medium-low heat. The larger the surface area of the pan, the more evenly the onions will cook. Add the onions, making sure to coat them evenly with the fat and spread them out for even cooking.

Now, the secret to perfect caramelization is a slow and steady approach. Cook the onions for about 30-45 minutes, occasionally stirring to prevent burning. If needed, deglaze the pan with a splash of water or broth to incorporate the flavorful fond that forms at the bottom. When the onions have reached a deep golden brown color and a jam-like consistency, you’ll know they’re ready. Season with salt and pepper, and voilà – you have beautifully caramelized onions for your French onion soup. Remember, the key is patience and gentle heat, so take your time and enjoy the process. Your soup will taste all the better for it!

Storage

Leftover French onion soup will keep in the fridge for up to 4 days in an airtight container. To reheat, just put it in the microwave for a few minutes on medium power or in a saucepan on the stovetop. You can also freeze the soup for up to 3 months, but you’ll want to let it thaw out before reheating.

Other Delicious Soup Recipes To Try

• Chicken Barley Soup
• Albondigas Soup
• Lasagna Soup
• Beef Barley Soup
• Italian Wedding Soup
• Lemon Rice and Chicken Soup
• Chicken Meatball Noodle Soup

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4.67 from 42 votes

French Onion Soup

Prep 20 minutes minutes

Cook 2 hours hours 10 minutes minutes

Total 2 hours hours 30 minutes minutes

8

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This French Onion Soup is a classic based on Julia Child‘s famous recipe. Buttery caramelized onions, rich and savory broth, cheesy toasted bread, this soup is flavorful and truly comforting.

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Ingredients

• ▢ 2 tablespoons olive oil
• ▢ 2 tablespoons butter (unsalted)
• ▢ 1½ pounds yellow onions (peeled, halved and thinly sliced)
• ▢ ½ teaspoon sugar
• ▢ 1 teaspoon salt
• ▢ 3 tablespoons all-purpose flour
• ▢ 1 tablespoon butter (unsalted)
• ▢ 6 cups beef broth (low sodium or no sodium added)
• ▢ 1 cup red wine (dry such as Pinot Noir, Côtes du Rhône or Merlot)
• ▢ 2 bay leaves
• ▢ 3 sprigs thyme
• ▢ 3 tablespoons cognac
• ▢ 8 slices french baguette
• ▢ 2 cups gruyere (shredded)
• ▢ ½ cup Parmesan cheese (grated)

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Instructions 

• Caramelize Onions: In a large heavy pot such as a Dutch oven, add the olive oil and 2 tbsp of butter. Cook on medium until butter melts. Add the onions and give them a stir to coat them in the oil. Cover the pot with a lid and cook for 20 minutes with the heat still on medium, stirring every few minutes. After 20 minutes the onions should be transparent.
• Remove the lid and stir in the sugar and salt. Continue cooking for another 40 minutes, stirring occasionally. The onions are done when they are a deep golden color and sweet. 
• Make a Roux: Add the flour, and remaining 1 tablespoon of butter and stir. Cook for about 2 or 3 minutes, just enough to cook the flour and remove that flour taste.
• Deglaze: Add 1 cup of the beef broth to the pot and stir. Cook for about 1 minute while stirring to scrape the bottom of the pot. You’ll see it evaporate almost immediately. 
• Add broth, wine and herbs: Add the rest of the broth to the pot, followed by the red wine, bay leaves and thyme sprigs. 
• Simmer: Bring to a boil, then turn down the heat and simmer for 30 minutes, uncovered. Discard bay leaves and thyme.
• Season and add cognac: Taste for seasoning and adjust with salt and pepper if needed. Stir in the cognac.
• Add bread and cheese: Top the soup with about 1 cup of gruyere cheese. Add the slices of bread over the cheese. I prefer to toast my bread first then add it to the soup. To toast the bread, lightly sprinkle the bread slices with some olive oil, transfer them to a baking sheet and toast them under broil for about 30 seconds to a minute per side. Top the soup with toasted bread, then top with remaining gruyere and parmesan cheese. 
• Melt cheese: Preheat your oven to 350°F (177°C). Transfer the pot to the oven and bake until the cheese melts and starts to brown, about 20 to 25 minutes. Ladle into bowls and serve.

Notes

1. Onions – I prefer to to use yellow onions because of their bright flavor and sweetness. Shallots are also great because they provide a really good balance of sweetness, with bright and deep flavors.
2. Beef Broth or Stock – If you’re not making your own stock, use a good quality beef broth, preferably with no salt added. This way you can control the salt in the soup yourself.
3. Wine – Use a red wine such as Pinot Noir, Côtes du Rhône, Cabernet Sauvignon, Merlot or a Malbec.
4. Cognac Alternative – If you don’t have cognac, use a brandy, or simply skip it.
5. Cheese – French Onion Soup demands Gruyere cheese because it’s rich, smooth and melts with ease!
6. Storage – Transfer French Onion Soup to an airtight container and store in the refrigerator for 3 to 4 days. Freeze it in covered airtight containers or heavy-duty freezer bags for up to 3 months.

Nutrition Information

Serving: 1servingCalories: 408kcal (20%)Carbohydrates: 27g (9%)Protein: 19g (38%)Fat: 21g (32%)Saturated Fat: 11g (69%)Polyunsaturated Fat: 2gMonounsaturated Fat: 8gTrans Fat: 0.2gCholesterol: 52mg (17%)Sodium: 1160mg (50%)Potassium: 601mg (17%)Fiber: 2g (8%)Sugar: 6g (7%)Vitamin A: 515IU (10%)Vitamin C: 7mg (8%)Calcium: 466mg (47%)Iron: 2mg (11%)

© Author Joanna Cismaru

Notice: Nutrition is auto-calculated for your convenience. Where relevant, we recommend using your own nutrition calculations.